The government has already rejected the automaker’s initial plan to fix the emissions issue in 2.0-liter TDI engines in nearly half a million vehicles. A plan to fix models with the 3.0-liter TDI V-6 was submitted earlier this month.

“We are committed to resolving these matters as quickly as possible,” Robert Giuffra, an attorney for the automaker, told Breyer during a hearing this week. Giuffra said Volkswagen was making progress in its efforts to reach a settlement with several government agencies including the Justice Department, the Environmental Protection Agency, and the California Air Resources Board.

Breyer indicated that Volkswagen has looked at several options including some that are “not the most advantageous for the company” and that the automaker would be making some difficult decisions with “serious consequences.” Although costly, one possibility the automaker previously mentioned included buybacks of affected vehicles.

Former FBI director Robert Mueller, named as a settlement adviser, has met with the senior Volkswagen engineer heading the fix. Now, the federal judge wants Mueller to also meet with the automaker’s top executives. In the meantime, Volkswagen has hired a German law firm to advise it about potential liabilities regarding the dieselgate scandal.

The automaker has also postponed its 2015 results and delayed an annual shareholders’ meeting because of the ongoing issue.